Eph-Ephrin signaling and focal adhesion kinase regulate actomyosin-dependent apical constriction of ciliary band cells
Eph-Ephrin signaling and focal adhesion kinase regulate actomyosin-dependent apical constriction of ciliary band cells
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DOI：
10.1242/dev.100123
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发表时间：
2014-03-01
期刊：
影响因子：
4.6
通讯作者：
Burke, Robert D.
中科院分区：
文献类型：
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作者：
Krupke, Oliver A.;Burke, Robert D.
顶端缩窄通常伴随着上皮层的向内折叠。近年来，在了解顶端缢缩的机制及其对形态发生过程的贡献方面取得了进展。海胆胚胎形成外胚层的一个专门区域，纤毛带，这是一条上皮，三到五个细胞宽，环绕口腔外胚层，并在幼虫游泳和进食中发挥作用。睫状带细胞表现出独特的顶端-基部伸长，具有狭窄的顶端，顶端带有纤毛，并且是平面极化的，因此纤毛从嘴部跳动。在这里，我们表明，丝状肌动蛋白和磷酸化肌球蛋白轻链是唯一分布在睫状带细胞。肌球蛋白磷酸化或肌动蛋白聚合的抑制扰乱了这种分布并阻断了顶端收缩。在睫状带形成过程中，Sp-Ephrin和Sp-Eph表达在假定的睫状带中重叠。Sp-Eph或Sp-Ephrin的敲低或Eph激酶抑制剂的治疗干扰肌动球蛋白网络、磷酸化FAK（pY（397）FAK）的积累和顶端收缩。Sp-Eph的胞质结构域与GST融合，含有一个报告为激酶死亡的氨基酸取代，将从胚胎裂解物中拉下pY（397）FAK。同样，pY（397）FAK与Sp-Eph以JNK依赖的平面极化方式共定位于睫状带的纬向顶端连接处，并且这种极化与顶端收缩无关。我们认为Sp-Eph和pY（397）FAK在顶端复合体中共同发挥作用，该复合体对于重塑肌动球蛋白以产生导致顶端收缩的向心力是必要的。睫状带细胞的形态发生是顶端收缩的一个独特例子，其中受体介导的细胞形状变化产生一条专门的组织，而不伴随上皮的折叠。
Apical constriction typically accompanies inward folding of an epithelial sheet. In recent years there has been progress in understanding mechanisms of apical constriction and their contribution to morphogenetic processes. Sea urchin embryos form a specialized region of ectoderm, the ciliary band, which is a strip of epithelium, three to five cells wide, encircling the oral ectoderm and functioning in larval swimming and feeding. Ciliary band cells exhibit distinctive apical-basal elongation, have narrow apices bearing a cilium, and are planar polarized, so that cilia beat away from the mouth. Here, we show that filamentous actin and phosphorylated myosin light chain are uniquely distributed in ciliary band cells. Inhibition of myosin phosphorylation or actin polymerization perturbs this distribution and blocks apical constriction. During ciliary band formation, Sp-Ephrin and Sp-Eph expression overlap in the presumptive ciliary band. Knockdown of Sp-Eph or Sp-Ephrin, or treatment with an Eph kinase inhibitor interferes with actomyosin networks, accumulation of phosphorylated FAK (pY(397)FAK), and apical constriction. The cytoplasmic domain of Sp-Eph, fused to GST and containing a single amino acid substitution reported as kinase dead, will pull down pY(397)FAK from embryo lysates. As well, pY(397)FAK colocalizes with Sp-Eph in a JNK-dependent, planar polarized manner on latitudinal apical junctions of the ciliary band and this polarization is dissociable from apical constriction. We propose that Sp-Eph and pY(397)FAK function together in an apical complex that is necessary for remodeling actomyosin to produce centripetal forces causing apical constriction. Morphogenesis of ciliary band cells is a unique example of apical constriction in which receptor-mediated cell shape change produces a strip of specialized tissue without an accompanying folding of epithelium.